This invention relates to an image processing apparatus using a surface model for generating a three-dimensional image on a display device, and more particularly to an image processing technology of mapping texture of color, design, pattern, etc to each polygon.
In the field of computer graphics, in particular, electronic game machines, a recent trend is to give operators realistic impressions by using a three-dimensional scene display technology.
FIG. 3 is a schematic block diagram showing a conventional image processing apparatus. This apparatus is comprised from a processor 10, a data memory 11 for storing texture data, a polygon mapping circuit 12, and a frame memory 13 for storing image data of one frame. The frame image data stored in the frame memory 13 is transmitted to display device (not shown).
In the conventional image processing apparatus, the processor 10 executes modeling transformation, projection transformation or the like transformation on the basis of operational data generated in accordance with the game program or operator's manipulation to create data of a polygon of a surface model and sends the data to the polygon mapping circuit 12.
The polygon mapping circuit 12 reads a texture data corresponding to a surface number of the polygon, executes mapping of the read texture on the polygon, and sends the texture-mapped polygon data to a frame memory 13. The frame memory 13 accumulates a predetermined number of texture-mapped polygon data to create image data of one frame and sends the one frame image data to the display device.
In the process of creating a surface model, hidden-surface elimination operation is executed. The hidden-surface elimination operation is generally carried out when two objects are overlapped with-each other, to discriminate a foreground object from a background object by giving priority to the former one between the two. The hidden-surface elimination operation is very complicated.
In the conventional image processing apparatus, texture mapping operation is executed for polygons of a surface model one after another. This will complicate the texture mapping. If a scene to be generated contains a greater number of overlapped objects, more calculation will be forcibly required for not only the hidden-surface elimination operation but also the texture mapping operation, thus resulting in an increased image processing time.
To solve this problem, for example, Japanese Unexamined Patent Publication No. 2-219184 disclose a parallel processing for hidden-surface elimination operation to reduce the time for elimination. However, such a parallel structure processing causes complicated structure, larger size, and higher costs.